Mobile wireless communication system

ABSTRACT

Provided is a mobile wireless communication system that improves response immediacy in a wireless communication system using an SCPC communication system. For this purpose, a base station and/or a plurality of mobile stations is provided with a number-of-channels switching means that monitors the communication state to create determination information for determining the necessity of switching the number of channels, and that switches the ratio of the number of channels for downlink communications and that for uplink communications, in a case where a change in the number of channels is necessary on the basis of the determination information.

This application is a National Stage Entry of PCT/JP2015/003677 filed onJul. 22, 2015, which claims priority from Japanese Patent Application2014-152993 filed on Jul. 28, 2014, the contents of all of which areincorporated herein by reference, in their entirety.

TECHNICAL FIELD

The present invention relates to a mobile wireless communication system.

BACKGROUND ART

In public wireless systems such as fire defense wireless systems,disaster defense wireless systems, and police wireless systems, a SingleChannel per Carrier (SCPC) system that allocates one signal channel toone carrier frequency is used in some cases (the following patentdocuments).

In such public wireless systems, there are a plurality of mobilestations in a region (communication area) covered by one base station.Communication from a base station to a mobile station is referred to asdownlink communication, and inversely, communication from the mobilestation to the base station is referred to as uplink communication.Signals used respectively are referred to as a downlink signal and anuplink signal.

For the public wireless systems, there are the following characteristicsand requests.

(1) An administrative unit such as a local prefectural government, and amunicipal government, or a cooperative or an association in which aplurality of these units are combined is operated as one unit.

(2) For each unit of these, there are main operations in which commandinformation and annunciation information is transmitted from the centerto terminals of an administrative organization via downlinkcommunication and a site situation is reported to the center from aterminal site via uplink communication. In other words, in downlinkcommunication, one-to-many simultaneous distribution such asbroadcasting is mainly performed, and in uplink communication,one-to-one individual communication is mainly performed.

(3) Therefore, when only downlink communication needs to be performed, areception-dedicated terminal (command receiver) is used. As such a case,a case is cited in which, for example, a fire company organization is auser in a fire defense wireless system.

(4) On the other hand, in uplink communication, it is desirable that notonly a base station but also another mobile station can intercept uplinkcommunication from a specific mobile station to share informationbetween the mobile stations.

To realize a public wireless system having these characteristics andrequests, allocation of frequency resources is necessary. There is anallocation method based on a hierarchical structure in which, forexample, a frequency band is broadly allocated to each administrativefunction such as fire defense, disaster defense, and police, andfurther, in the frequency band, a minute frequency band (frequencychannel) for each regional organization is allocated.

In this case, to prevent radio wave interference among wirelesscommunication systems of neighboring regions, it is necessary toallocate different frequency channels to respective regionalorganizations where radio waves are reachable. Therefore, it isdesirable to ensure as many frequency channels as possible. However, thefrequency resource is limited, and therefore in the SCPC system, anoccupied frequency bandwidth of each frequency channel is suppressed ina range where voice signal transmission is possible, and a digitalcommunication system (digital modulation and encoding) has beenintroduced as a suppression means.

As a specific example, in a digital fire defense wireless system inJapan, a frequency bandwidth of 6.25 kHz is allocated to one frequencychannel, and π/4 shift Quadrature Phase Shift Keying (QPSK) modulationas a digital modulation method, bandwidth compression, and furtherencoding for information concealment are performed.

Different frequencies are used for downlink communication and uplinkcommunication that configures duplex communication with the downlinkcommunication to become a pair, respectively, but frequency channels ofthe same band width are basically allocated and the same digitalmodulation method and encoding method are used.

CITATION LIST Patent Literature

[PTL 1]

-   Japanese Laid-open Patent Publication No. H9-2008161

[PTL 2]

-   Japanese Laid-open Patent Publication No. H6-284077

[PTL 3]

-   Japanese Laid-open Patent Publication No. H6-140968

[PTL 4]

-   Japanese Laid-open Patent Publication No. 2013-135432

[PTL 5]

-   Japanese Laid-open Patent Publication No. 2007-281947

[PTL 6]

-   International Publication No. WO2013/042454

SUMMARY OF INVENTION Technical Problem

However, in the above-described public wireless systems, there have beencases in which emergency responses (immediate responses) are difficult.

When a mobile station responds, in uplink communication, to informationtransmitted from a base station in downlink communication, there may bea plurality of mobile stations that desire uplink communicationtransmission to the base station having transmitted the downlinkcommunication. However, since numbers of downlink/uplink frequencychannels simultaneously usable at a certain time are the same, it isnecessary for a mobile station that desires uplink communicationtransmission to confirm that a channel for uplink communication is notbeing used by another mobile station and, upon being used, to wait untilthe channel becomes unused.

In other words, when a mobile station responds to informationtransmitted from a base station, it is necessary for another mobilestation to perform no communication (a channel is unused). Responseimmediacy is impaired by a time until the channel becomes unused.

Therefore, a first object of the present invention is to provide amobile wireless communication system in which response immediacy isimproved.

Further, in the above-described public wireless systems, there has beena problem that a power consumption of a mobile station increases.

To uplink communication transmitted from a mobile station, a frequencychannel of the same band width as for downlink communication transmittedfrom a base station is allocated, and the same digital modulation methodand encoding method as for the downlink communication are used. Further,in both the base station and the mobile station, downlink communicationand uplink communication frequently share an antenna, and thereforethere is not a large difference between downlink communication anduplink communication in antenna gain and radio wave propagation.Therefore, to achieve, in uplink communication, the same communicationquality as in downlink communication, it is necessary for the mobilestation to transmit, via uplink communication, the equivalent power as awireless power transmitted by the base station via downlinkcommunication. As a result, a power consumption of the mobile stationincreases, and heat generation associated with the power consumptionalso increases.

On the other hand, although the mobile station needs to endure a hightemperature environment, compared with the base station, a reduced sizeis needed to ensure portability and therefore heat releasing performanceis constrained. Further, in a disaster occurrence situation, it isdifficult to ensure a power supply, and therefore it is necessary to beable to reduce power consumption, compared with that in a normalsituation and perform drive using a battery for a long period.

Therefore, a second object of the present invention is to provide amobile wireless communication system including a mobile station in whichpower consumption and heat generation associated with the powerconsumption are small.

Further, in the above-described public wireless systems, there has beena problem that when a mechanism for encoding and decoding fails, therehas been a high possibility that it is difficult for an operator tocommunicate.

Encoding and decoding used in a public wireless system prioritizebandwidth compression performance and concealment performance, andtherefore are based on processing in which it is assumed that advancedencoding and decoding processing, i.e. high-speed operation using anelectronic circuit can be used.

In transmission of information, a button operation and utteranceinformation of an operator is encoded and transmitted by a deviceconfiguring the present system. In reception of information, theinformation encoded at the time of transmission is converted, by adevice configuring the present system, to a physical event recognizableby the operator through the five senses so that the operator canrecognize the information. However, in a situation where these publicwireless systems are specifically needed in a disaster occurrencesituation and the like, due to breakage resulting from a mechanicalcause such as vibrations or an impact, or breakage or data errorsresulting from an electromagnetic cause produced by lightning orelectric sparks, the mechanism for encoding or conversion fails, andthen it becomes difficult to perform transmission and reception in somecases.

However, even when a failure is occurring in such conversion, it may bepossible to emit and stop wireless radio waves of an own station or todiscriminate an emission and a stop of wireless radio waves by anotherbase station or mobile station.

Therefore, a third object of the present invention is to provide amobile wireless communication system including an alternativeencoding/decoding means capable of continuing communication by anoperator even when a failure is occurring in the mechanism for encodingor decoding.

Solution to Problem

To solve the problems, a mobile communication system including a basestation and a plurality of mobile stations that communicate with thebase station is characterized in that at least one of the base stationor the plurality of mobile stations includes a number-of-channelsswitching means that monitors a communication state and createsdetermination information for determining a necessity of switching anumber of channels, and that switches, when it is necessary to changethe number of channels on the basis of the determination information, aratio of numbers of channels for downlink communication and uplinkcommunications.

Further, to solve the problems, a mobile communication system includinga base station and a plurality of mobile stations that communicate withthe base station includes a transmission power control means configuredto switch a ratio of numbers of channels for downlink communication anduplink communication and control, in accordance with a change of atransmission bandwidth produced as the result of the switching,transmission power.

Further, to solve the problems, a mobile communication system includinga base station and a plurality of mobile stations that communicate withthe base station includes an encoding method switching means and amodulation method switching means configured to switch an encodingmethod and a modulation method corresponding to the encoding method incooperation with a switch of a ratio of numbers of channels for downlinkcommunication and uplink communication.

Advantageous Effects of Invention

According to the present invention, a time until a channel becomesunused can be shortened, and therefore response immediacy is improved.

Further, according to the present invention, transmission power can becontrolled in accordance with a change of a transmission band, andtherefore power consumption and heat generation associated therewith arereduced.

Further, according to the present invention, an alternativeencoding/decoding means is included, and therefore communication can becontinued even when a mechanism for encoding or decoding fails.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram of a mobile wireless communication systemaccording to the present exemplary embodiment.

FIG. 2 is a block diagram of a mobile station.

FIG. 3 is a block diagram of a receiver in which a channel selectionunit is included in a first demodulator.

FIG. 4 is a block diagram of a base station.

FIG. 5 is a block diagram of an instruction terminal device.

FIG. 6 is a block diagram of a mobile wireless communication systemaccording to a second exemplary embodiment.

FIG. 7 is a block diagram of a mobile wireless communication system inwhich there are two or more base stations.

FIG. 8 is a diagram exemplifying a narrowband frequency channel.

DESCRIPTION OF EMBODIMENTS First Exemplary Embodiment

Exemplary embodiments of the present invention will be described. FIG. 1is a block diagram of a mobile wireless communication system 2Aaccording to the present exemplary embodiment. The mobile wirelesscommunication system 2A includes an instruction terminal device 10, abase station 20, and mobile stations 30 (30 a, 30 b). In FIG. 1, twomobile stations 30 are illustrated, but there may be three or moremobile stations 30.

Outlined communication steps in the mobile wireless communication system2A are as follows. First, the mobile station 30 generates an uplinksignal and transmits the generated uplink signal via wirelesscommunication. The base station 20 and another mobile station 30 receivethe transmitted uplink signal. In the following description, acommunication pattern in which an uplink signal from the mobile station30 is received by another mobile station 30 will be expressed as adirect wave communication.

The base station 20 transmits the uplink signal received from the mobilestation 30 to the instruction terminal device 10 via wired or wirelesscommunication. The instruction terminal device 10 receives the uplinksignal from the base station 20.

On the other hand, the instruction terminal device 10 generates adownlink signal and transmits the generated downlink signal to the basestation 20 via wired or wireless communication, and the base station 20receives the transmitted signal. The base station 20 transmits thedownlink signal received from the instruction terminal device 10 to eachmobile station 30 via wireless communication. Each mobile station 30receives the downlink signal from the base station 20.

(1) Mobile Station 30

Next, the mobile station 30 in the mobile wireless communication system2A that performs such communication will be described. FIG. 2 is a blockdiagram of the mobile station 30.

The mobile station 30 includes a control unit 103, a transmitter 104, afirst receiver 105 for downlink signal reception, a second receiver 106for uplink signal interception, a duplexer 107, and an antenna 108.

(1-A) Configuration of Transmitter

The transmitter 104 includes a voice signal processing unit (TX-AF) 141,a baseband (BB) signal processing unit (TX-BB) 142, a high-frequencysignal processing unit (TX-RF) 143, and an input unit (KEY) 144 for anarrowband frequency channel, and transmits an uplink signal to the basestation 20.

The voice signal processing unit 141 includes a voice input unit (MIC)141 a.

Further, the BB signal processing unit (TX-BB) 142 includes an encodingunit (ENC) 142 a and a modulator (MOD) 142 b.

Further, the high-frequency signal processing unit (TX-RF) 143 includesa frequency converter (MIX) 143 a, a high-frequency front end (FE) unit(FE) 143 b, and an oscillator (LO) 143 c.

A voice signal that is an analog signal input from the voice input unit141 a such as a microphone and the like is converted to a transmissiondigital voice signal G11 by the voice input unit 141 a and is input tothe encoding unit 142 a of the BB signal processing unit 142.

The encoding unit 142 a encodes the transmission digital voice signalG11 on the basis of an encoding method specifying signal P11 from thecontrol unit 103 and outputs the encoded signal to the modulator 142 bas an encode voice signal G12.

The encoding method specifying signal P11 is information for specifyinga component (hardware(HW)) and an algorithm (software(SW)) used forencoding processing and is generated by the control unit 103 on thebasis of registration information previously recorded on the controlunit 103, request information transmitted from a communication partner,determination information determined in accordance with a type of datatransmitted as a transmission signal, determination informationdetermined on the basis of quality (error rate, data rate, latency)necessary for a transmission signal, and determination informationdetermined on the basis of monitoring information (electric fieldintensity, error rate) of a reception signal.

On the other hand, a transmission digital data signal G13 from the inputunit 144 is input to the encoding unit 142 a and the modulator 142 b.The input unit 144 can include a plurality of keys such as a keyboard ofa general QWERTY layout or a numeric keypad, a touch sensor or a touchpanel, a proximity sensor, and a camera system that discriminatesgestures of an operator.

The encoding unit 142 a encodes the transmission digital data signal G13and outputs the encoded signal to the modulator 142 b as an encode datasignal G14.

The modulator 142 b converts at least one of the encode voice signal G12or the encode data signal G14 to a transmission analog BB signal(transmission ABB signal) or a transmission intermediate-frequencysignal (transmission IF signal) that is an analog signal on the basis ofa modulation method specifying signal P12. The modulator 142 b outputsthe converted signal to the frequency converter 143 a of thehigh-frequency signal processing unit 143 as a modulation signal G15.

As a generation method for the modulation signal G15, a method forinputting an input digital signal to an analog filtering unit andwaveform-shaping the input signal to a necessary analog signal waveform,a method for simplifying an analog filtering unit for analog waveformshaping by temporarily generating a digital sampling waveformcorresponding to an analog signal waveform to be needed via digitaloperation, followed by D/A conversion, and a method for generating ananalog waveform of an intermediate-frequency band via analog or digitaloperation is applicable.

The modulation method specifying signal P12 is information forspecifying a component (HW) and an algorithm (SW) used for modulationprocessing. The control unit 103 generates the modulation methodspecifying signal P12 by on the basis of registration informationpreviously recorded on the control unit 103, request informationtransmitted from a communication partner, determination informationdetermined in accordance with a type of data transmitted as atransmission signal, determination information determined on the basisof quality (error rate, data rate, latency) necessary for datatransmitted as a transmission signal, and determination informationdetermined on the basis of monitoring information (electric fieldintensity, error rate) of a reception signal.

When a component (HW) or an algorithm (SW) used for modulationprocessing is specified by the modulation method specifying signal P12,it is possible to select modulation processing appropriate for acommunication partner, modulation processing optimum for a type of datatransmitted as a transmission signal and quality to be needed, andmodulation processing suitable for a radio wave propagation situationestimated from monitoring information of a reception signal and improvepower efficiency and communication quality.

The modulation signal G15 from the modulator 142 b and a transmissionlocal oscillation signal (transmission LO signal) G16 from theoscillator 143 c are input to the frequency converter 143 a. Thetransmission LO signal G16 is a signal for determining a carrierfrequency as a wireless signal. The frequency converter 143 a mixes themodulation signal G15 and the transmission LO signal G16 and outputs theresulting signal to the high-frequency FE unit 143 b as a transmissionRF signal (transmission high-frequency signal) G17.

A frequency setting signal P13 is information that is input to theoscillator 143 c and specifies a frequency of the transmission LO signalG16. The control unit 103 generates the frequency setting signal P13 onthe basis of transmission frequency information input by an operation ofan operator or transmission frequency information associated withreception frequency information determined by search processing whenthere is a reception signal search function.

Further, mixing processing executed by the frequency converter 143 a isprocessing for performing frequency conversion of the modulation signalG15 and the transmission LO signal G16 by analog mixing processing andgenerating the transmission RF signal G17.

The high-frequency FE unit 143 b performs power amplification and gainadjustment power-supply-controlled for power saving (elimination ofundesired waves from the transmission RF signal G17 and amplification upto a power necessary for transmission) for the transmission RF signalG17 on the basis of a power supply/gain control signal P14 generated bythe control unit 103 and outputs the resulting signal to the duplexer107.

The duplexer 107 outputs the transmission RF signal G17 to the antenna108. The antenna 108 transmits the input transmission RF signal G17 tothe base station 20 and another mobile station 30 as an uplink signalradio wave.

At least one of the modulator 142 b or the oscillator 143 c can receivetransmission narrowband frequency channel specifying information(TX_NB_FCH specifying information) from the control unit 103. At leastone of the modulator 142 b or the oscillator 143 c includes a functionfor outputting, when the transmission narrowband frequency channelspecifying information has been input, a modulation signal or anoscillation signal having a frequency based on contents of theinformation.

(1-B) Configuration of First Receiver

The first receiver 105 includes a first voice signal processing unit(RX-AF) 151, a first baseband (BB) signal processing unit (RX-BB) 152, afirst high-frequency signal processing unit (RX-RF) 153, a first display(DISP) 154, and a first oscillator (LO) 155, and receives a downlinksignal from the base station 20.

The first voice signal processing unit (RX-AF) 151 includes a firstvoice output unit (SPK) 151 a.

Further, the first BB signal processing unit (RX-BB) 152 includes afirst decoder (DEC) 152 a and a first demodulator (DEM) 152 b.

The first high-frequency signal processing unit (RX-RF) 153 includes afirst channel selection unit (SEL) 153 a, a first frequency converter(MIX) 153 b, and a first high-frequency front end (FE) unit (FE) 153 c.

A DL reception RF signal (base station wave reception high-frequencysignal) G21 from the base station 20, the signal being acquired in theantenna 108, is input to the first high-frequency FE unit 153 c of thefirst high-frequency signal processing unit 153 via the duplexer 107.

The first high-frequency FE unit 153 c performs power amplification andgain adjustment power-supply-controlled for power saving for the DLreception RF signal G21 on the basis of a power supply/gain controlsignal P21 generated by the control unit 103 and inputs the resultingsignal to the first frequency converter 153 b.

The DL reception RF signal G21 and a DL reception LO signal (basestation wave reception local oscillation signal) G22 from the firstoscillator 155 are input to the first frequency converter 153 b. Thefirst frequency converter 153 b performs frequency conversion for the DLreception RF signal G21 by the DL reception LO signal G22, generates aDL reception ABB signal (base station wave reception analog basebandsignal) or a DL reception IF signal (base station wave receptionintermediate-frequency signal) that is an analog signal. The firstfrequency converter 153 b outputs the generated signal to the firstchannel selection unit 153 a as a frequency conversion signal G23.

At that time the first oscillator 155 generates the DL reception LOsignal G22 on the basis of a frequency setting signal P22. The frequencysetting signal P22 is information for specifying a frequency of areception local oscillation signal and is generated by the control unit103 on the basis of reception frequency information input by anoperation of an operator or reception frequency information determinedby search processing when there is a reception signal search function.

The first channel selection unit 153 a can receive base station wavereception narrowband frequency channel specifying information (DL_RXNB_FCH specifying information) from the control unit 103. The firstchannel selection unit 153 a includes a function for extractingcomponents of a frequency and a band based on contents of the basestation wave reception narrowband frequency channel specifyinginformation in the frequency conversion signal G23 when the base stationwave reception narrowband frequency channel specifying information hasbeen input. The first channel selection unit 153 a can be also includedin at least one of the first demodulator 152 b or the first oscillator155. FIG. 3 is a block diagram of a receiver in which the first channelselection unit 153 a in FIG. 2 is included in the first demodulator 152b. In FIG. 3, as a part of the function of the first demodulator 152 b,an extraction function is included. When the first channel selectionunit 153 a is included in the first oscillator 155 in FIG. 2, anextraction function is realized by frequency selection.

In FIG. 2 again, the first demodulator 152 b converts the frequencyconversion signal G23 to at least one of an encoded base station wavereception digital voice signal or an encoded base station wave receptiondigital data signal on the basis of a demodulation method specifyingsignal P23 and outputs the resulting signal to the first demodulator 152a as a demodulation signal G24.

The demodulation method specifying signal P23 is information forspecifying a component (HW) and an algorithm (SW) used for demodulationprocessing. The control unit 103 generates the demodulation methodspecifying signal P23 on the basis of registration informationpreviously recorded on the control unit 103, request informationtransmitted from a communication partner, and determination informationdetermined by the control unit 103 on the basis of monitoringinformation (electric field intensity, error rate) of a receptionsignal.

When a component (HW) or an algorithm (SW) used for demodulationprocessing is specified by the demodulation method specifying signalP23, it is possible to select demodulation processing appropriate for acommunication partner, demodulation processing optimum for a type ofdata to be obtained as a reception signal and quality to be needed for areception signal, and demodulation processing suitable for a radio wavepropagation situation estimated from monitoring information of areception signal and improve communication quality.

The first decoder 152 a decodes a demodulation signal G24 on the basisof a decoding method specifying signal P24 and outputs the decodedsignal to the first voice output unit 151 a of the first voice signalprocessing unit 151 and the first display 154 as a decode signal G25.

The decode signal G25 output to the first voice output unit 151 a is asignal corresponding to the base station wave reception digital voicesignal. Further, the decode signal G25 output to the first display 154is a signal corresponding to the encoded base station wave receptiondigital data signal.

The decoding method specifying signal P24 is information for specifyinga component (HW) and an algorithm (SW) used for decoding processing. Thecontrol unit 103 generates the decoding method specifying signal P24 onthe basis of registration information previously recorded on the controlunit 103, request information transmitted from a communication partner,and determination information determined by the control unit 103 on thebasis of monitoring information (electric field intensity, error rate)of a reception signal.

When a component (HW) or an algorithm (SW) used for decoding processingis specified by the decoding method specifying signal P24, it ispossible to select decoding processing appropriate for a communicationpartner, decoding processing optimum for a type of data to be obtainedas a reception signal and quality to be needed for a reception signal,and decoding processing suitable for a radio wave propagation situationestimated from monitoring information of a reception signal and improvecommunication quality.

The first voice output unit 151 a converts the input decode signal G25corresponding to the base station wave reception digital voice signal toa voice and outputs the voice. Further, the first display 154 convertsthe input decode signal G25 corresponding to the base station wavereception digital data signal to base station wave narrowband frequencychannel information and outputs the information.

(1-C) Configuration of Second Receiver

The second receiver 106 includes a second voice signal processing unit(RX-AF) 161, a second baseband (BB) signal processing unit (RX-BB) 162,a second high-frequency signal processing unit (RX-RF) 163, a seconddisplay (DISP) 164, and a second oscillator (LO) 165, and receives adirect wave signal from another mobile station 30.

The second voice signal processing unit (RX-AF) 161 includes a secondvoice output unit (SPK) 161 a.

Further, the second BB signal processing unit (RX-BB) 162 includes asecond decoder (DEC) 162 a and a second demodulator (DEM) 162 b.

The second high-frequency signal processing unit (RX-RF) 163 includes asecond channel selection unit (SEL) 163 a, a second frequency converter(MIX) 163 b, and a second high-frequency front end (FE) unit (FE) 163 c.

A UL reception RF signal (direct wave reception high-frequency signal)G31 from another mobile station 30, the signal being acquired in theantenna 108, is input to the second high-frequency FE unit 163 c of thesecond high-frequency signal processing unit 163 via the duplexer 107.The second high-frequency FE unit 163 c performs power amplification andgain adjustment power-supply-controlled for power saving for the ULreception RF signal G31 on the basis of a power supply/gain controlsignal P21′ generated by the control unit 103 and outputs the resultingsignal to the second frequency converter 163 b.

The UL reception RF signal G31 and a UL reception LO signal (direct wavereception local oscillation signal) G32 from the second oscillator 165are input to the second frequency converter 163 b. The second frequencyconverter 163 b performs frequency conversion for the UL reception RFsignal G31 by the UL reception LO signal G32, generates a UL receptionABB signal (direct wave reception analog baseband signal) or a ULreception IF signal (direct wave reception intermediate-frequencysignal) that is an analog signal. The second frequency converter 163 boutputs the generated signal to the second channel selection unit 163 aas a frequency conversion signal G33.

At that time, the second oscillator 165 generates the UL reception LOsignal G32 on the basis of a frequency setting signal P22′. Thefrequency setting signal P22′ is information for specifying a frequencyof a reception local oscillation signal and is generated by the controlunit 103 on the basis of reception frequency information input by anoperation of an operator or reception frequency information determinedby search processing when there is a reception signal search function.

The second channel selection unit 163 a can receive direct wavereception narrowband frequency channel specifying information (UL_RXNB_FCH specifying information) from the control unit 103. The secondchannel selection unit 163 a includes a function for extractingcomponents of a frequency and a band based on contents of the directwave reception narrowband frequency channel specifying information inthe frequency conversion signal G33 when the direct wave receptionnarrowband frequency channel specifying information has been input. Thesecond channel selection unit 163 a can be also included in at least oneof the second demodulator 162 b or the second oscillator 165. When thesecond channel selection unit 163 a is included in the seconddemodulator 162 b, an extraction function is included as a part of thefunction of the second demodulator 162 b. When the second channelselection unit 163 a is included in the second oscillator 165, anextraction function is realized by frequency selection.

The second demodulator 162 b converts the frequency conversion signalG33 to at least one of an encoded direct wave reception digital voicesignal or an encoded direct wave reception digital data signal on thebasis of a demodulation method specifying signal P23′ and outputs theresulting signal to the second demodulator 162 a as a demodulationsignal G34.

The demodulation method specifying signal P23′ is information forspecifying a component (HW) and an algorithm (SW) used for demodulationprocessing. The control unit 103 generates the demodulation methodspecifying signal P23′ on the basis of registration informationpreviously recorded on the control unit 103, request informationtransmitted from a communication partner, and determination informationdetermined by the control unit 103 on the basis of monitoringinformation (electric field intensity, error rate) of a receptionsignal.

When a component (HW) or an algorithm (SW) used for demodulationprocessing is specified by the demodulation method specifying signalP23′, it is possible to select demodulation processing appropriate for acommunication partner, demodulation processing optimum for a type ofdata to be obtained as a reception signal and quality to be needed for areception signal, and demodulation processing suitable for a radio wavepropagation situation estimated from monitoring information of areception signal and improve communication quality.

The second decoder 162 a decodes the demodulation signal G34 on thebasis of a decoding method specifying signal P24′ and outputs thedecoded signal to the second voice output unit 161 a of the second voicesignal processing unit 161 and the second display 164 as a decode signalG35.

The decode signal G35 output to the second voice output unit 161 a is asignal corresponding to the direct wave reception digital voice signal.Further, the decode signal G35 output to the second display 164 is asignal corresponding to the encoded direct wave reception digital datasignal.

The decoding method specifying signal P24′ is information for specifyinga component (HW) and an algorithm (SW) used for decoding processing. Thecontrol unit 103 generates the decoding method specifying signal P24′ onthe basis of registration information previously recorded on the controlunit 103, request information transmitted from a communication partner,and determination information determined by the control unit 103 on thebasis of monitoring information (electric field intensity, error rate)of a reception signal.

When a component (HW) or an algorithm (SW) used for decoding processingis specified by the decoding method specifying signal P24′, it ispossible to select decoding processing appropriate for a communicationpartner, decoding processing optimum for a type of data to be obtainedas a reception signal and quality to be needed for a reception signal,and decoding processing suitable for a radio wave propagation situationestimated from monitoring information of a reception signal and improvecommunication quality.

The second voice output unit 161 a converts the input decode signal G35corresponding to the direct wave reception digital voice signal to avoice and outputs the voice. Further, the second display 164 convertsthe input decode signal G35 corresponding to the direct wave receptiondigital data signal to direct wave narrowband frequency channelinformation and outputs the information.

(2) Base Station

Next, the base station 20 will be described. FIG. 4 is a block diagramof the base station 20.

The base station 20 of the present invention includes a control unit203, a transmitter (TX) 204, a receiver (RX) 205 for uplink signalreception, a duplexer 207, and an antenna 208.

(2-1) Function of Transmitter

The transmitter (TX) 204 includes a baseband (BB) signal processing unit(TX-BB) 242 and a high-frequency signal processing unit (TX-RF) 243 andtransmits a downlink signal.

The BB signal processing unit (TX-BB) 242 includes an encoding unit(ENC) 242 a and a modulator (MOD) 242 b. Further, the high-frequencysignal processing unit (TX-RF) 243 includes a frequency converter (MIX)243 a, a high-frequency front end (FE) unit (FE) 243 b, and anoscillator (LO) 243 c.

The control unit 203 inputs an input signal G211 of at least one of atransmission digital voice signal or a transmission digital data signalinput from an external network to the encoding unit 242 a of the BBsignal processing unit 242.

As the external network, a local area network (LAN) or a publiccommunication network is cited, and as a transmission source oftransmission information (a transmission digital voice signal and atransmission digital data signal), the instruction terminal device 10and a line control device is cited.

The encoding unit 242 a encodes the input signal G211 of at least one ofa transmission digital voice signal or a transmission digital datasignal on the basis of an encoding method specifying signal P41. Theencoding unit 242 a outputs the encoded transmission digital voicesignal and the encoded transmission digital data signal to the modulator242 b as an encode signal G212 for each signal.

The encoding method specifying signal P41 is information for specifyinga component (hardware (HW) and an algorithm (software (SW) used forencoding processing. The control unit 203 generates the encoding methodspecifying signal P41 on the basis of registration informationpreviously recorded on the control unit 203, request informationtransmitted from a communication partner, determination informationdetermined in accordance with a type of data transmitted as atransmission signal, determination information determined on the basisof quality (error rate, data rate, latency) necessary for a transmissionsignal, and determination information determined on the basis ofmonitoring information (electric field intensity, error rate) of areception signal.

The modulator 242 b converts the encode signal G212 to a transmissionanalog BB signal (transmission ABB signal) or a transmissionintermediate-frequency signal (transmission IF signal) that is an analogsignal on the basis of a modulation method specifying signal P42. Themodulator 242 b outputs the converted signal to the frequency converter243 a of the high-frequency signal processing unit 243 as a modulationsignal G213.

As a generation method for the modulation signal G213, a method forinputting an input digital signal to an analog filtering unit andwaveform-shaping the input signal to a necessary analog signal waveform,a method for simplifying an analog filtering unit for analog waveformshaping by temporarily generating a digital sampling waveformcorresponding to an analog signal waveform to be needed via digitaloperation, followed by D/A conversion, and a method for generating ananalog waveform of an intermediate-frequency band via analog or digitaloperation is applicable.

The modulation method specifying signal P42 is information forspecifying a component (HW) and an algorithm (SW) used for modulationprocessing. The control unit 203 generates the modulation methodspecifying signal P42 on the basis of registration informationpreviously recorded on the control unit 203, request informationtransmitted from a communication partner, determination informationdetermined on the basis of a type of data transmitted as a transmissionsignal, determination information determined on the basis of quality(error rate, data rate, latency) necessary for data transmitted as atransmission signal, and determination information determined on thebasis of monitoring information (electric field intensity, error rate)of a reception signal.

The modulation signal G213 from the modulator 242 b and a transmissionlocal oscillation signal (transmission LO signal) G214 from theoscillator 243 c are input to the frequency converter 243 a. Thetransmission LO signal G214 is a signal for determining a carrierfrequency as a wireless signal. The frequency converter 243 a mixes themodulation signal G213 and the transmission LO signal G214 and outputsthe resulting signal to the high-frequency FE unit 243 b as atransmission RF signal (transmission high-frequency signal) G215.

A frequency setting signal P43 is information that is input to theoscillator 243 c and specifies a frequency of the transmission LO signalG214. The control unit 203 generates the frequency setting signal P43 onthe basis of transmission frequency information previously allocated tothe base station 20 to determine a transmission frequency.

Further, mixing processing executed by the frequency converter 243 a isprocessing for performing frequency conversion of the modulation signalG213 and the transmission LO signal G214 via analog mixing operation andgenerating the transmission RF signal G215.

The high-frequency FE unit 243 b performs power amplification and gainadjustment power-supply-controlled for power saving (elimination ofundesired waves from the transmission RF signal G215 and amplificationup to a power necessary for transmission) for the transmission RF signalG215 on the basis of a power supply/gain control signal P44 generated bythe control unit 203 and outputs the resulting signal to the duplexer207.

The duplexer 207 outputs the transmission RF signal G215 to the antenna208. The antenna 208 radiates the input transmission RF signal G215toward the mobile station 30 as a downlink signal radio wave.

(2-2) Configuration of Receiver

The receiver 205 includes a baseband (BB) signal processing unit (RX-BB)252, a high-frequency signal processing unit (RX-RF) 253, and anoscillator (LO) 255, and receives an uplink signal from the mobilestation 30.

The BB signal processing unit (RX-BB) 252 includes a decoder (DEC) 252 aand a demodulator (DEM) 252 b.

Further, the high-frequency signal processing unit (RX-RF) 253 includesa frequency converter (MIX) 253 b and a high-frequency front end (FE)unit (FE) 253 c.

A reception RF signal (reception high-frequency signal) G221 from themobile station 30, the signal being acquired in the antenna 208, isinput to the high-frequency FE unit 253 c of the high-frequency signalprocessing unit (RX_RF) 253 through the duplexer 207.

The reception high-frequency FE unit 253 c performs power amplificationand gain adjustment power-supply-controlled for power saving for thereception RF signal G221 on the basis of a power supply/gain controlsignal P51 generated by the control unit 203 and inputs the resultingsignal to the frequency converter 253 b.

The reception RF signal G221 and a reception local oscillation signal(reception LO signal) G222 from the oscillator (LO) 255 are input to thefrequency converter 253 b. The frequency converter 253 b performsfrequency conversion for the reception RF signal G221 by the receptionLO signal G222, generates a reception analog BB signal (reception ABBsignal) or a reception intermediate-frequency signal (reception IFsignal) that is an analog signal, and outputs the generated signal tothe demodulator 252 b as a frequency conversion signal G223.

The oscillator 255 generates the reception LO signal G222 on the basisof a frequency setting signal P52 from the control unit 203 and outputsthe generated signal. The frequency setting signal P52 is informationthat is input to the oscillator 255 and specifies a frequency of thereception LO signal G222, and is generated by the control unit 203 onthe basis of reception frequency information previously allocated to thebase station 20 to determine a reception frequency.

The demodulator 252 b converts the frequency conversion signal G223 toat least one of an encoded reception digital voice signal or an encodedreception digital data signal on the basis of a demodulation methodspecifying signal P53 and outputs the resulting signal to thedemodulator 252 a as a demodulation signal G224.

The demodulation method specifying signal P53 is information forspecifying a component (HW) and an algorithm (SW) used for demodulationprocessing. The control unit 203 generates the demodulation methodspecifying signal P53 on the basis of registration informationpreviously recorded on the control unit 203, request informationtransmitted from a communication partner, and determination informationdetermined by the control unit 203 on the basis of monitoringinformation (electric field intensity, error rate) of a receptionsignal.

When a component (HW) or an algorithm (SW) used for demodulationprocessing is specified by the demodulation method specifying signalP53, it is possible to select demodulation processing appropriate for acommunication partner, demodulation processing optimum for a type ofdata to be obtained as a reception signal and quality to be needed for areception signal, and demodulation processing suitable for a radio wavepropagation situation estimated from monitoring information of areception signal and improve communication quality.

The decoder 252 a decodes the demodulation signal G224 on the basis of adecoding method specifying signal P54 and outputs the decoded signal tothe control unit 203 as a decode signal G225.

The decoding method specifying signal P54 is information for specifyinga component (HW) and an algorithm (SW) used for decoding processing. Thecontrol unit 203 generates the decoding method specifying signal P54 onthe basis of registration information previously recorded on the controlunit 203, request information transmitted from a communication partner,and determination information determined by the control unit 203 on thebasis of monitoring information (electric field intensity, error rate)of a reception signal.

When a component (HW) or an algorithm (SW) used for decoding processingis specified by the decoding method specifying signal P54, it ispossible to select decoding processing appropriate for a communicationpartner, decoding processing optimum for a type of data to be obtainedas a reception signal and quality to be needed for a reception signal,and decoding processing suitable for a radio wave propagation situationestimated from monitoring information of a reception signal and improvecommunication quality.

The control unit 203 outputs the decode signal G225 to an externalnetwork. As the external network, a LAN or a public communicationnetwork is cited, and as a transmission destination of the receptioninformation, the instruction terminal device 10 and a line controldevice is cited.

The demodulator 252 b includes a channel selection means (FREQ SEL) (notillustrated). The channel selection means includes a function that canreceive narrowband frequency channel specifying information (NB_FCHspecifying information) from the control unit 203 and extract acomponent of a frequency and a band on the basis of contents of thenarrowband frequency channel specifying information in the frequencyconversion signal G223 when the narrowband frequency channel specifyinginformation has been input. The channel selection means can also beincluded in the oscillator 255. When the channel selection means isincluded in the oscillator 255, an extraction function can be realizedby frequency selection.

(3) Instruction Terminal Device

Next, the instruction terminal device 10 will be described. FIG. 5 is ablock diagram of the instruction terminal device 10.

The instruction terminal device 10 of the present invention includes acontrol unit 303, a transmitter (TX) 310, a receiver (RX) 320, a displayunit (DISP) 330, and a channel selection unit (SEL) 340, andcommunicates with the mobile station 30 via the base station 20. Thetransmitter 310 includes a voice input unit (MIC) 311 and a transmissionsignal processing unit (AF) 312. Further, the receiver 320 includes avoice output unit (SPK) 321 and a reception signal processing unit (AF)322.

(3-1) Configuration of Transmitter

The voice input unit 311 of the transmitter 310 outputs a voice to thetransmission voice processing unit 312 as a transmission voice signalG301 that is an analog signal.

The transmission voice processing unit 312 converts the transmissionvoice signal G301 to a digital signal and outputs the digital signal tothe control unit 303 as a transmission digital voice signal G302.

The control unit 303 outputs the transmission digital voice signal G302to an external network. As the external network, a LAN or a publiccommunication network can be exemplified, and as a transmissiondestination of the transmission information, the base station 20 and aline control device can be exemplified.

(3-2) Configuration of Receiver

The control unit 303 input at least one of a reception digital voicesignal or a reception digital data signal from an external network,outputs a reception digital voice signal G311 to the reception signalprocessing unit 322, and outputs a reception digital data signal G321 tothe display unit 330.

As an example of the external network, a LAN or a public communicationnetwork is cited, and as a transmission source of the input information,the base station 20 and a line control device is cited.

The reception signal processing unit 322 converts the reception digitalvoice signal G311 that is a digital signal to a reception voice signalG312 that is an analog signal and outputs the converted signal to thevoice output unit 321.

The voice output unit 321 converts the reception voice signal G312 to areception voice and outputs the voice. Further, the display unit 330converts the reception digital data signal G321 to an image or a voiceand outputs the image or the voice.

The channel selection unit 340 generates narrowband frequency channelspecifying information (NB_FCH specifying information) G331 and outputsthe generated information to the control unit 303.

The channel selection unit 340 generates the narrowband frequencychannel specifying information G331 on the basis of a narrowbandfrequency channel selection instruction of an instructor (operator). Thenarrowband frequency channel is a channel having a narrow frequency bandas exemplified in FIG. 8. In FIG. 8, a case in which there are aplurality of channels having, for example, a band of 500 Hz is cited.Each narrowband frequency channel is assigned with an identificationcode (number). The narrowband frequency channel specifying informationG331 includes the identification code.

The narrowband frequency channel specifying information G331 is outputto the control unit 203 of the base station 20 through an externalnetwork from the control unit 303 and is converted to narrowbandfrequency channel specifying information inside the base station.Further, via the base station 20, the information is also output to thecontrol unit 103 of the mobile station 30 and converted to narrowbandfrequency channel specifying information inside the mobile station.

(4) Operations of the Entire System

Next, the operations of the above-described mobile wirelesscommunication system 2A will be described using the configuration ofFIG. 1 as an example. In FIG. 1, there are an instruction terminaldevice 10, a base station 20, and a plurality of mobile stations 30(here, a mobile station 30 a and a mobile station 30 b). Each mobilestation 30 generates an uplink signal that is a wireless signal on thebasis of information intended to be transmitted by an operator who is atransmitter and transmits the generated signal to the base station 20via wireless communication.

Contents of the uplink signal include voice information, imageinformation, other data information, and control information oncommunication. These pieces of information can be roughly classifiedaccording to necessities of immediacy for the respective pieces ofinformation. The immediacy indicates that a receiver can receiveinformation substantially at the same time as transmission ofinformation by a transmitter, as represented, for example, by atelephone call.

The base station 20 converts the uplink signal that is a wireless signalreceived from the mobile station 30 to a wired signal or a wirelesssignal of another format and transmits the converted signal to theinstruction terminal device 10.

The instruction terminal device 10 received the uplink signal from thebase station 20 and executes, for an operator as a receiver, processing(e.g. reproduction or recording) for contents (voice information, imageinformation, and other data information) included in the signal.

Inversely, the instruction terminal device 10 generates a downlinksignal that is a wired signal or a wireless signal of a format differentfrom that used between the base station 20 and the mobile station 30 onthe basis of information intended to be transmitted by an operator as atransmitter and transmits the generated signal to the base station 20.

Contents of the downlink signal also include voice information, imageinformation, other data information, and control information oncommunication, and these pieces of information can be also roughlyclassified according to necessities of immediacy for the respectivepieces of information as in the case of the uplink signal.

The base station 20 receives the downlink signal from the instructionterminal device 10, converts the received signal to a downlink signalthat is a wireless signal, and transmits the converted signal to aplurality of mobile stations 30 via wireless communication.

Each mobile station 30 receives the downlink signal from the basestation 20 and executes, for an operator as a receiver, processing (e.g.reproduction or recording) for contents (voice information, imageinformation, and other data information) included in the signal.

An uplink signal that is a wireless signal generated by a certain mobilestation 30 (e.g. the mobile station 30 a) is also received by anothermobile station 30 (e.g. the mobile station 30 b) as a direct wavecommunication between the mobile stations 30.

The mobile station 30 having received the signal executes, for anoperator as a receiver, processing (e.g. reproduction or recording) forcontents (voice information, image information, and other datainformation) included in the signal.

Next, with reference to FIG. 8, a frequency map in wirelesscommunication performed between the base station 20 and the mobilestation 30 will be described using an SCPC system for frequency divisionduplex as an example.

In the SCPC system for frequency division duplex in which a frequencyband is separated in uplink/downlink communications, as illustrated inFIG. 8, on downlink communication from the base station 20 to the mobilestation 30, a band (here, as an example, a band width is assumed to be6.25 kHz) previously set at a frequency fH as a center is assumed as onechannel. Further, on uplink communication from the mobile station 30 tothe base station 20 in a normal situation, a band having centerfrequency fL different from fH and the same band-width as the downlinksignal is assumed as one channel. These are used as a pair (1:1). Such a(1:1) relation in which numbers of channels in uplink/downlinkcommunications are the same will be expressed as a number-of-channelsequal state.

In FIG. 8, a band of 6.25 kHz bandwidth in which the frequency fL iscentered in uplink communication is further divided into a plurality ofnarrowbands (here, as an example, a case of a band width of 500 Hz isindicated), and numbers of uplink and downlink channels are assumed tobe 1:N (N is an integer equal to or larger than 2). Such a (1:N)relation in which numbers of channels in uplink/downlink communicationsare not the same will be expressed as a number-of-channels unequalstate. Such an operation can be performed when, for example, many uplinkcommunication channels are necessary in a disaster occurrence situation.

In the present exemplary embodiment, the encoder 242 a or the decoder252 a of the base station 20 monitors communication, the monitoringresult is transmitted to the control unit 203, and the control unit 203determines switching (number-of-channels switching) between anumber-of-channels equal state and a number-of-channels unequal stateand a ratio in an unequal number state. As a monitoring result that thedetermination is based on, a degree of congestion of communication, adegree of necessity of immediacy in a plurality of uplinkcommunications, or the like can be exemplified.

Further, in the present exemplary embodiment, the demodulator 252 b orthe decoder 252 a of the base station 20 monitors a number-of-channelsequal/unequal state and a ratio in a number-of-channels unequal state inthe frequency conversion signal G223 or the demodulation signal G224 bymeasuring an energy distribution in a frequency spectrum, and themonitoring results are transmitted to the control unit 203, whereby thecontrol unit 203 can recognize a switching situation between anumber-of-channels equal state and a number-of-channels unequal stateand a ratio in a number-of-channels unequal state having already becomeoperative in an uplink communication channel. As a result, it ispossible to automatically control number-of-channels switching inaccordance with a situation of the uplink communication channel.

An operator of the base station 20 may determine number-of-channelsswitching. The operator can recognize communication congestion bymonitoring a usage situation (a ratio of time being used forcommunication) for each channel. Further, immediacy can be recognized bymonitoring usage applications (voice communication, data communication,and the like).

Further, the number-of-channels switching may be determined byreceiving, by the control unit 203 of the base station 20, based onswitching request information received from a line control device (notillustrated) or the instruction terminal device 10.

The base station 20 makes, on the basis of the number-of-channelsswitching determination, a request to the mobile station 30 forswitching for causing the mobile station 30 to communicate in anumber-of-channels equal r state of (1:1) in a normal situation and tocommunicate in a number-of-channels unequal state of (1:N) in anemergency situation such as a disaster occurrence situation. Theswitching request information is transmitted by being included in acontrol signal generally transmitted/received between the base station20 and the mobile station 30. The mobile station 30 having received thecontrol signal switches an operation setting (number-of-channelssetting) of a transmitter in the own station.

Further, the base station 20 switches, on the basis of a determinationresult of switching necessity, an operation setting of a receiver of theown station at the time of uplink signal reception from the mobilestation 30.

The switching request information may be generated by the instructionterminal device 10 or another device other than the base station 20. Itis possible for the base station 20 to convert the information to acontrol signal and transmit the control signal to the mobile station 30.

In a number-of-channels unequal state, the band for one uplink channelis narrow (here, a band width is assumed to be 500 Hz), and therefore asymbol rate of a signal transmittable in the band decreasescorrespondingly to the bandwidth. On the other hand, it is possible toaccommodate, in the band, a signal of Amplified Shift Keying (ASK)modulation for intermittently continuing a carrier using e.g. MorseCode.

At the time of reception, at least a power of reception band noiseproportional to a reception signal bandwidth is superposed with areception signal power. When the reception signal band is narrow, areception band noise power (a product of a level of a noise floor ofthermal noise and a reception signal bandwidth) is reduced. In otherwords, to obtain the same carrier-power to noise-power ratio (C/N), whenthe signal bandwidth decreases from 6.25 kHz to 500 Hz, an influence ofreception band noise does not change even upon transmission powerreduction to approximately 1/12.

As a result, advantageous effects in which consumed power can bereduced, further a battery lasts long, and size reduction and costreduction are achieved for heat release since heat generation decreasesare obtained.

(4-2) Operation of Mobile Station

Next, an operation of the mobile station 30 will be described withreference to FIG. 2.

(4-2-1) Operation of Transmitter

A voice of an operator of a mobile station is converted to a voicesignal by the voice input unit 141 a, and a transmission digital voicesignal G11 is generated.

The encoder 142 a encodes the transmission digital voice signal G11 inaccordance with a coding method such as an Adaptive Differential PulseCode Modulation (ADPCM) method, a Code-Excited Linear Prediction (CELP)method, a voice CODEC, and the like specified by a coding methodspecifying signal P11 from the control unit 103 and outputs the encodedsignal to the modulator 142 b as an encode voice signal G12.

On the other hand, the input unit 144 is, for example, a keyboard foroutputting digital encode data or a switch for outputting ON/OFF states.The input unit 144 generates a transmission digital data signal G13 onthe basis of an operation of an operator, and then the encoder 142 aoutputs the generated signal to the modulator 142 b as an encode datasignal G14.

The modulator 142 b modulates the encode voice signal G12 and the encodedata signal G14 and outputs the modulated signal to the frequencyconverter 143 a as a modulation signal G15.

The frequency converter 143 a mixes the modulation signal G15 and atransmission LO signal G16 and generates a transmission RF signal G17.

The high-frequency FE unit 143 b performs undesired wave eliminationfrom the transmission RF signal G17 and power amplification and outputsthe resulting signal to the duplexer 107.

The duplexer 107 performs demultiplexing on the basis of frequencies toshare one antenna 108 by signals of different frequency bands.

The antenna 108 converts the input transmission RF signal G17 to a radiowave propagating in a space and radiates the radio wave toward the basestation 20 and another mobile station 30.

At least one of the modulator 142 b or the oscillator 143 c can receive,from the control unit 103, transmission narrowband frequency channelspecifying information (TX_NB_FCH specifying information) for specifyinga part of a plurality of set transmission narrowband frequency channels.Then, the modulator 142 b outputs a modulation signal of a frequencybased on contents thereof and the oscillator 143 c outputs anoscillation signal of a frequency based on the contents.

The TX_NB_FCH specifying information is generated on the basis ofinformation on what transmission narrowband frequency channel is used,obtained from, for example, an operation of an operator, an informationinput operation (as an output of the channel selection unit 340) in theinstruction terminal device 10, or determination processing of thecontrol unit 103.

(4-2-2) Operation of First Receiver

The antenna 108 acquires a DL reception RF signal G21 (base station wavereception high-frequency signal) from the base station 20 and outputsthe acquired signal to the duplexer 107. The duplexer 107 guides the DLreception RF signal G21 to the first high-frequency FE unit 153 c of thefirst high-frequency signal processing unit 153.

The first high-frequency FE unit 153 c eliminates undesired waves fromthe DL reception RF signal G21, also performs amplification to thesignal up to a level necessary for demodulation, and outputs theamplified signal. The first oscillator 155 generates a DL reception LOsignal G22 (base station wave reception local oscillation signal) to bea carrier for demodulation or frequency conversion.

The first frequency converter 153 b performs frequency conversion byanalog mixing operation for the DL reception RF signal G21 and the DLreception LO signal G22 and generates a DL reception ABB signal (basestation wave reception analog BB signal) or a DL reception IF signal(base station wave reception intermediate-frequency signal). Thesesignals each are output as a frequency conversion signal G23.

The first demodulator 152 b demodulates the frequency conversion signalG23 and outputs the demodulated signal as a demodulation signal G24. Thefirst decoder 152 a decodes the demodulation signal G24 and generates a(decoded) base station wave reception digital voice signal and a(decoded) base station wave reception digital data signal and outputsthe generated signals as decode signals G25, respectively.

The first voice signal processing unit 151 performs D/A conversion forthe decode signal G25 corresponding to the base station wave receptiondigital voice signal and generates a base station wave reception analogvoice signal.

The first voice output unit 151 a receives the base station wavereception analog voice signal, converts the signal to a voice that is asound wave, and outputs the voice to an operator from, for example, aspeaker or an earphone.

Further, the first display 154 coverts the decode signal G25corresponding to the base station wave reception digital data signal tobase station wave narrowband frequency channel information and displaysthe information to the operator. The base station wave narrowbandfrequency channel information may be displayed on the first display 154as an image or output using voices, vibrations, or the like.

The first channel selection unit 153 a extracts components of aspecified frequency and band in the frequency conversion signal G23 onthe basis of base station wave reception narrowband frequency channelspecifying information (DL_RX NB_FCH specifying information) from thecontrol unit 103.

When included in the first demodulator 152 b, the first channelselection unit 153 a extracts components of a specified frequency andband as a part of the function of the first demodulator 152 b. Further,when included in the first oscillator 155, the first channel selectionunit 153 a extracts components of a specified frequency and band byfrequency selection.

The control unit 103 receives information on what base station wavereception narrowband frequency channel is used, obtained from, forexample, an operation of the operator, an operation (as an output of thechannel selection unit 340) of the instruction terminal device 10, ordetermination processing of the control unit. On the basis of theinformation, the control unit 103 generates DL_RX NB_FCH specifyinginformation.

(4-2-3) Operation of Second Receiver

The antenna 108 acquires a UL reception RF signal G31 (direct wavereception high-frequency signal) from another mobile station 30 andoutputs the signal to the duplexer 107. The duplexer 107 guides the ULreception RF signal G31 to the second high-frequency FE unit 163 c ofthe second high-frequency signal processing unit 163.

The second high-frequency FE unit 163 c eliminates undesired waves fromthe UL reception RF signal G31, also performs amplification to thesignal up to a level necessary for demodulation, and outputs theamplified signal.

The second oscillator 165 generates a UL reception LO signal G32 (directwave reception local oscillation signal) to be a carrier fordemodulation or frequency conversion.

The second frequency converter 163 b performs frequency conversion byanalog mixing operation for the UL reception RF signal G31 and the ULreception LO signal G32 and generates a UL reception ABB signal (directwave reception analog BB signal) or a UL reception IF signal (directwave reception intermediate-frequency signal). These signals are outputas frequency conversion signals G33, respectively.

The second demodulator 162 b demodulates the frequency conversion signalG33 and outputs the demodulated signal as a demodulation signal G34. Thesecond decoder 162 a decodes the demodulation signal G34 and generates a(decoded) direct wave reception digital voice signal and a (decoded)direct wave reception digital data signal and outputs the generatedsignals as decode signals G35, respectively.

The second voice signal processing unit 161 performs D/A conversion forthe decode signal G35 corresponding to the direct wave reception analogvoice signal and generates a direct wave reception analog voice signal.

The second voice output unit 161 a receives the direct wave receptiondigital analog voice signal, converts the signal to a voice that is asound wave, and outputs the voice to an operator from, for example, aspeaker or an earphone.

Further, the second display 164 coverts the decode signal G35corresponding to the direct wave reception digital data signal to directwave narrowband frequency channel information and displays theinformation to the operator. The direct wave narrowband frequencychannel information may be displayed on the second display 164 as animage or output using voices, vibrations, or the like.

The second channel selection unit 163 a extracts components of aspecified frequency and band in the frequency conversion signal G33 onthe basis of direct wave reception narrowband frequency channelspecifying information (UL_RX NB_FCH specifying information) from thecontrol unit 103.

When included in the second demodulator 162 b, the second channelselection unit 163 a extracts components of a specified frequency andband as a part of the function of the second demodulator 162 b. Further,when included in the second oscillator 165, the second channel selectionunit 163 a extracts components of a specified frequency and band byfrequency selection.

The control unit 103 receives information on what direct wave receptionnarrowband frequency channel is used, obtained from, for example, anoperation of an operator, an operation (as an output of the channelselection unit 340) of the instruction terminal device 10, ordetermination processing of the control unit. On the basis of theinformation, the control unit 103 generates UL_RX NB_FCH specifyinginformation.

(4-3) Operation of Base Station

Next, in FIG. 4, an operation of the base station 20 of the presentexemplary embodiment will be described in detail.

Here, a case in which the base station 20 of the present exemplaryembodiment includes a control unit 203, a transmitter 204, a receiver205, a duplexer 207, and an antenna 208 is used as an example.

(4-3-1) Operation of Transmitter

The encoder 242 a receives an input signal G211 of a transmissiondigital voice signal and a transmission digital data signal input viathe control unit 203, followed by encoding, and outputs the encodedsignal to the modulator 242 b as an encode signal G212. The transmissiondigital voice signal is encoded in accordance with a coding method suchas an ADPCM method, a CELP method, a voice CODEC, and the like specifiedby a coding method specifying signal P41 from the control unit 203.

The modulator 242 b modulates the encode signal G212 and outputs themodulated signal as a modulation signal G213. The oscillator 243 cgenerates a transmission LO signal G214 for determining a frequency of acarrier as a wireless signal.

The frequency converter 243 a performs frequency conversion by analogmixing operation for the modulation signal G213 and the transmission LOsignal G214 and outputs the resulting signal as a transmission RF signalG215.

The high-frequency FE unit 243 b eliminates undesired waves from thetransmission RF signal G215, also performs amplification to the signalup to a power necessary for transmission, and outputs the resultingsignal to the duplexer 207.

The duplexer 207 performs demultiplexing on the basis of frequencies toshare one antenna 208 by signals of different frequency bands.

The antenna 208 converts the input transmission RF signal G215 to aradio wave propagating in a space and radiates the radio wave toward themobile station 30.

(4-3-2) Operation of Receiver

The antenna 208 acquires a reception RF signal G221 (receptionhigh-frequency signal) from the mobile station 30 and outputs theacquired signal to the duplexer 207. The duplexer 207 guides thereception RF signal G221 to the high-frequency FE unit 253 c of thehigh-frequency signal processing unit 253.

The high-frequency FE unit 253 c eliminates undesired waves from thereception RF signal G221, also performs amplification to the signal upto a level necessary for demodulation, and outputs the amplified signal.The oscillator 255 generates a reception LO signal G222 to be a carrierfor demodulation or frequency conversion.

The frequency converter 253 b performs frequency conversion by analogmixing operation for the reception RF signal G221 and the reception LOsignal G222 and outputs the resulting signal as a frequency conversionsignal G223.

The demodulator 252 b demodulates the frequency conversion signal G223and outputs the demodulated signal as a demodulation signal G224. Thedecoder 252 a decodes the demodulation signal G224 and outputs thedecoded signal to the control unit 203 as a decode signal G225.

The control unit 203 outputs the decode signal G225 to an externalnetwork. As the external network, a LAN or a public communicationnetwork is cited, and as a transmission destination of receptioninformation, the instruction terminal device 10 and a line controldevice is cited.

At least one of the demodulator 252 b or the oscillator 255 includes achannel selection function (not illustrated). The channel selectionfunction extracts components of a specified frequency and band in thefrequency conversion signal G223 on the basis of narrowband frequencychannel specifying information (NB_FCH specifying information) from thecontrol unit 203. When included in the demodulator 252 b, the channelselection function extracts components of a specified frequency and bandas a part of the function of the demodulator 252 b. Further, whenincluded in the oscillator 255, the channel selection function extractscomponents of a specified frequency and band by frequency selection.

The control unit 203 receives information on what narrowband frequencychannel is used, obtained from, for example, a request signal from themobile station, determination processing of the control unit, or thechannel selection unit 340 of the instruction terminal device 10 throughthe control unit. On the basis of the information, the control unit 203generates NB_FCH specifying information.

(4-4) Operation of Instruction Terminal Device

Next, in FIG. 5, an operation of the instruction terminal device 10 ofthe present exemplary embodiment will be described in detail.

(4-4-1) Operation of Transmitter

A voice that is a sound wave is converted to an analog voice signal bythe voice input unit 311 and output as a transmission voice signal G301.

The transmission signal processing unit 312 performs A/D conversion forthe transmission voice signal G301 and outputs the converted signal tothe control unit 303 as a transmission digital voice signal G302. Thecontrol unit 303 outputs the transmission digital voice signal G302 toan external network. As the external network, a LAN or a publiccommunication network is cited, and as a transmission destination oftransmission information, the base station 20 and a line control deviceis cited.

(4-4-2) Operation of Receiver

The control unit 303 receives at least one of a reception digital voicesignal or a reception digital data signal from an external network. Thecontrol unit 303 outputs a reception digital voice signal G311 to thereception signal processing unit 322, and outputs a reception digitaldata signal G321 to the display unit 330. As the external network, a LANor a public communication network is cited, and as a transmission sourceof input information, the base station 20 and a line control device iscited.

The reception signal processing unit 322 performs D/A conversion for thereception digital voice signal G311 and outputs the converted signal asa reception voice signal G312. The voice output unit 321 converts thereception voice signal G312 to a voice that is a sound wave and outputsthe voice to an operator using a speaker, an earphone, or the like.

As described above, a plurality of mobile stations can perform uplinkcommunication at the same time, and therefore even when a mobile stationis about to start performing uplink communication and also anothermobile station is using a band thereof, it is unnecessary to wait untilthe band becomes unused, resulting in an improvement in responseimmediacy.

Further, since different communication bandwidths are assigned to uplinkcommunication and downlink communication, it is unnecessary for a mobilestation to transmit, via uplink communication, the same power as a powertransmitted by a base station via downlink communication, and thereforea consumed power necessary for transmission in uplink communication canbe reduced. As a result, it is possible to achieve size reduction,endurance against wide environment temperature conditions, adaptationsto severe heat radiation requirements, and long-term drive using abattery.

Further, a code (e.g. Morse Code) recongnizable by human with a sense ofhearing, vision, and touch is introduced, and therefore it is possiblefor human to directly recognize encoded information using the fivesenses. Further, a transmission function featuring small consumed powerand small heat generation became able to be introduced, and therefore itis possible to mount an uplink communication transmission function whilemaintaining an advantage as a command receiver.

Second Exemplary Embodiment

A second exemplary embodiment of the present invention will bedescribed. For the same components as in the first exemplary embodiment,the same reference signs are used, and description thereof will beomitted, as appropriate. In the first exemplary embodiment, a case inwhich the base station 20 performs transmission/reception via onefrequency channel has been described. In contrast, in the presentexemplary embodiment, it is possible for the base statin 20 to performtransmission/reception via two or more frequency channels.

FIG. 6 is a block diagram of such a mobile wireless communication system2B. A line control device 40 is additionally provided between theinstruction terminal device 10 and the base station 20, compared withthe mobile wireless communication system 2A illustrated in FIG. 1.

The line control device 40 connects, on the basis of specifyinginformation for specifying a specific mobile station 30 from theinstruction terminal device 10, the instruction terminal device 10 to afrequency channel used by the specified mobile station 30.

Further, FIG. 7 is a block diagram of a mobile wireless communicationsystem 2C in which there are two or more base stations 20. In the mobilewireless communication system 2C, one or more mobile stations 30 existfor each base station 20 and are transmittable to/receivable from eachbase station 20.

Therefore, the line control device 40 is additionally provided betweenthe instruction terminal device 10 and the base station 20. The linecontrol device 40 connects, on the basis of specifying information for aspecific mobile station 30 from the instruction terminal device 10, theinstruction terminal device 10 to a base station 20transmittable/receivable by the specified mobile station 30.

Thereby, using two or more frequency channels, transmission/reception inaccordance with a communication state can be performed.

While the present invention has been described with reference toexemplary embodiments (and examples) thereof, the present invention isnot limited to these exemplary embodiments (and examples). Theconstitution and details of the present invention can be subjected tovarious modifications which can be understood by those skilled in theart, without departing from the scope of the present invention.

This application is based upon and claims the benefit of priority fromJapanese patent application No. 2014-152993, filed on Jul. 28, 2014, thedisclosure of which is incorporated herein in its entirety by reference.

REFERENCE SIGNS LIST

-   -   2A to 2C Mobile wireless communication system    -   10 Instruction terminal device    -   20 Base station    -   30 (30 a, 30 b) Mobile station    -   40 Line control device    -   103 Control unit    -   104 Transmitter    -   105 First receiver    -   106 Second receiver    -   107 Duplexer    -   108 Antenna    -   141 Voice signal processing unit (TX-AF)    -   141 a Voice input unit (MIC)    -   142 BB signal processing unit (TX-BB)    -   142 a Encoding unit (ENC)    -   142 b Modulator (MOD)    -   143 High-frequency signal processing unit (TX-RF)    -   143 a Frequency converter (MIX)    -   143 b High-frequency FE unit (FE)    -   143 c Oscillator (LO)    -   144 Input unit (KEY)    -   151 First voice signal processing unit (RX-AF)    -   151 a First voice output unit (SPK)    -   152 First BB signal processing unit (RX-BB)    -   152 a First decoder (DEC)    -   152 b First demodulator (DEM)    -   153 First high-frequency signal processing unit (RX-RF)    -   153 a First channel selection unit (SEL)    -   153 b First frequency converter (MIX)    -   153 c First high-frequency FE unit (FE)    -   154 First display (DISP)    -   155 First oscillator (LO)    -   161 Second voice signal processing unit (RX-AF)    -   161 a Second voice output unit (SPK)    -   162 Second BB signal processing unit (RX-BB)    -   162 a Second decoder (DEC)    -   162 b Second demodulator (DEM)    -   163 Second high-frequency signal processing unit (RX-RF)    -   163 a Second channel selection unit (SEL)    -   163 b Second frequency converter (MIX)    -   163 c Second high-frequency FE unit (FE)    -   164 Second display (DISP)    -   165 Second oscillator (LO)    -   203 Control unit    -   204 Transmitter (TX)    -   205 Receiver (TX)    -   207 Duplexer (DUP)    -   208 Antenna    -   242 BB signal processing unit (TX-BB)    -   242 a Encoding unit (ENC)    -   242 b Modulator (MOD)    -   243 High-frequency signal processing unit (TX-RF)    -   243 a Frequency converter (MIX)    -   243 b High-frequency FE unit (FE)    -   243 c Oscillator (LO)    -   252 BB signal processing unit (RX-BB)    -   252 a Decoder (DEC)    -   252 b Demodulator (DEM)    -   253 High-frequency signal processing unit (RX-RF)    -   253 b Frequency converter (MIX)    -   253 c High-frequency FE unit (FE)    -   255 Oscillator (LO)    -   303 Control unit    -   310 Transmitter (TX)    -   311 Voice input unit (MIC)    -   312 Transmission signal processing unit (AF)    -   320 Receiver (RX)    -   321 Voice output unit (SPK)    -   322 Reception signal processing unit (AF)    -   330 Display unit (DISP)    -   340 Channel selection unit (SEL)

What is claimed is:
 1. A mobile communication system comprising a basestation and a plurality of mobile stations that communicate with thebase station, wherein at least one of the base station or the pluralityof mobile stations includes a number-of-channels switching unit thatmonitors a communication state and creates determination information fordetermining a necessity of switching a number of channels, and thatswitches, when it is necessary to change the number of channels on thebasis of the determination information, a ratio of numbers of channelsfor downlink communication and uplink communication, by dividing abandwidth of a channel.
 2. The mobile communication system according toclaim 1, wherein the number-of-channels switching unit switches theratio of numbers of channels to a state of 1:1 and a state of 1:N (whereN is a positive integer equal to or larger than 2).
 3. The mobilecommunication system according to claim 1, wherein the base stationtransmits a control signal for making an instruction for setting theratio of numbers of channels for downlink communication and uplinkcommunication to a specific mobile station of the plurality of mobilestations.
 4. The mobile communication system according to claim 3,wherein the specific mobile station sets a transmission narrowbandfrequency channel for transmission for a transmitter on the basis of thecontrol signal.
 5. The mobile communication system according to claim 3,wherein the base station sets a reception narrowband frequency channelfor reception for a receiver on the basis of the control signal.
 6. Themobile communication system according to claim 4, wherein thetransmission narrowband frequency channel is subjected to ASKmodulation.
 7. The mobile communication system according to claim 3,wherein the determination information is generated by an instructionterminal device.
 8. The mobile communication system according to claim5, wherein the transmission narrowband frequency channel is subjected toASK modulation.